Triazolopyridines. Part 5. The reactions of 1,2,3-triazolo[5,1 -a]isoquinoline: a new route to 1,3-disubstituted isoquinolines

Abstract

Substitution of 1,2,3-triazolo[1,5-a] isoquinoline by electrophiles occurs at position 1, lithiation at position 5. The lithio derivative (8) reacts with electrophiles to give 5-substituted derivatives (9)–(13). Hydrolytic ring opening of compound (4) and of compound (9) occurs with loss of nitrogen, thus providing a synthesis of 1,3-disubstituted isoquinolines. The conversion of a 3,4-disubstituted triazoloquinoline into a 2,3-disubstituted derivative of quinoline is described. A direct synthesis of N,N-dialkylquinolyl-(21) and N,N-dialkylisoquinolyl-acetamides (24) and (25) and the conversion of compound (21) into N,N-diethyltriazoloquinoline-4-carboxamide (3) has been achieved.